Using laser beams to pull an object towards the
source of the beam is perhaps best known as a fictional technology
on Star Trek. As is the case with
many modern-day technologies, though, what once was fiction is now
a reality: A duo out of NYU recently published a paper that
describes a technique they developed for this very technology: a
device that uses energy to pull an object towards it.

Researchers have made a breakthrough in
Bessel Beam research that could one day lead to the technology we
saw in the Star Trek TV series.

Background on the breakthrough

David Grier, a professor of physics, and David
Ruffner, a graduate student, are the brains behind the research,
which they based off a form of laser called the “Bessel
Beam.” The technology is named after its creator,
Friedrich Bessel, and basically it’s a type of laser that
directs light in concentric circles around a single dot, as opposed
to acting as a single beam.

What’s special about the Bessel Beam
is that, unlike your regular, run-of-the-mill laser, the light that
comes from it — at the dot — is not diffracted.
As a result, the beam can be reformed should it encounter an object
or obstruction in its path.

Ruffner and Grier discovered that this very
property can actually be used to pull a particle toward the source
of the laser beam.

Updating previous research

Last year, a Chinese research team calculated
that it might be possible to direct a Bessel Beam at a particle and
fine-tune it so that after the light strikes the front part, it
reforms, and strikes again on the back end. The researchers
theorized that this transferring of energy would wind up pushing
the particle back toward the source, with the end result looking
like a tractor beam.

Ruffner and Grier tried their hand at this
research and, while it didn’t work immediately, what they
discovered as a more effective alternative was using two Bessel
beams at once with a lens that bent both beams slightly to cause
them to overlap one another. Doing this resulted in a sort-of
strobe effect: light alternated on and off the back end of the
particle. This, in turn, provided enough energy to push the
stationary particle back toward the light source.

The end result is a device, of sorts, that when
viewed with the naked eye, provides the illusion of pulling a
particle toward the source device.

Video

David Grier was kind enough to provide
Electronic Products with a video of the technology, describing it
as follows:

“The grayscale movie at the bottom is
the data stream from our holographic video microscope that shows
two silica spheres being transported by two independent optical
conveyors that we embedded in a single beam of light. Each video
frame is a hologram of the spheres, which we can analyze to measure
the spheres’ positions. The plot above the movie shows
the spheres’ trajectories, to scale. The colored orbs
indicate the spheres’ actual positions in each frame.
From this, you can see that we’re moving one sphere up
the conveyor beam while we simultaneously move the other down. We
could have moved them both in either direction. This shows how much
control we can exert.”

Outlook

The team’s proof-of-concept
demonstration moves the spheres a total distance of just under 100
micrometers, which is huge given the fact that no one else has ever
been able to do something like this before. Next, Grier and Ruffner
want to increase the range, first to a millimeter, then to a full
meter. Once they achieve the latter goal, Grier explains, there
will be more applications to which this technology can be applied,
including noncontact environmental monitoring and industrial
process control.

Once they go beyond a kilometer, the team
figures the technology can be used to solve several problems that
NASA is presently facing in their cometary and planetary
missions.